Age Threshold of 50 for New Zoster Vaccine Not Cost-Effective: Study

By Will Boggs MD

NEW YORK (Reuters Health) - The new Advisory Committee on Immunization Practices (ACIP) guideline that recommends the new recombinant adjuvanted zoster subunit vaccine (RZV) over the live attenuated zoster vaccine (ZVL) and lowers the vaccination age to 50 years is not cost-effective, according to a new analysis.

"ACIP's recommendations assumed that all patients would complete both doses of the recombinant vaccine," Dr. Phuc Le from the Cleveland Clinic in Ohio told Reuters Health by email. "If that isn't the case, and it almost certainly is not, then the recommendations are unlikely to be cost-effective. That is because a single dose of the vaccine is not that effective. Waiting (until the patient is a little older) to get the vaccine made it cost-effective, even if only half the patients follow through with the second dose."

Dr. Le and Dr. Michael B. Rothberg used their previous Markov model to compare costs and quality-adjusted life-years (QALY) for RZV versus no vaccination with variation of vaccination age from 50 to 59 years. They calculated incremental cost-effectiveness ratios (ICERs) with willingness-to-pay thresholds of $50,000/QALY and $100,000/QALY.

In this model, at age 50 years, RZV had an ICER of $151,430/QALY, which didn't decline below the $100,000/QALY threshold until the vaccination age reached 53.2 years and didn't decline below the $50,000/QALY threshold until the vaccination age reached 57.1 years.

Higher adherence to the second dose made RZV cost-effective at younger ages, but in probabilistic sensitivity analysis, RZV at 50 years of age had only a 23% chance of being cost-effective, according to the July 9th JAMA Internal Medicine online report.

Administering an immediate booster with RZV to individuals previously vaccinated with ZVL, another ACIP recommendation, had an ICER greater than $100,000/QALY at all ages and would be reasonable only if adherence was 100%.

Waiting five years after ZVL at age 60 years had a 75% chance of being cost-effective.

"Our findings suggest that average patients should wait until age 55 years to get the recombinant vaccine," Dr. Le said. "For average patients who were vaccinated with the live attenuated vaccine, they should wait at least five years to get a booster."

"The current recommendations should apply only to patients who are 100% sure they will get both doses," she said. "Based on experience with other adult vaccines, many patients will not get both doses. This might be particularly true if the patient has a serious local reaction, which is pretty common with this vaccine."

Dr. C. Bernie Good from University of Pittsburgh Medical Center Health Plan's Center for Value Based Pharmacy Initiatives told Reuters Health by email, "This report illustrates nicely the variation that can occur when different groups assess the same issue for cost-effectiveness. Cost-effectiveness for the RZV vaccine varies from $12,000/quality adjusted life year (industry analysis) to $83,000 (another industry analysis), with the estimates by Le and Rothberg and the CDC in between."

"This underscores the importance of examining the assumptions used to develop the analysis, as very disparate results can be reported," he said. "Physicians should view all cost-effectiveness analyses with these caveats in mind."

"Regardless of whether one chooses to offer vaccination for zoster prevention at age 50 or 55, the new RZV vaccine should be routinely offered to patients, as it is safe and effective," Dr. Good said. "The importance of following up with patients to make certain that they get the second shot is illustrated by the cost-effectiveness analysis, which indicates greater cost-effectiveness when both shots are received. Older patients especially benefit from vaccination, as the prevalence and adverse consequences of zoster increase dramatically with age."

The Centers for Disease Control and Prevention (CDC) did not respond to a request for comments.

SOURCE: https://bit.ly/2KSV9Bd

JAMA Intern Med 2018.

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